1. Field of the Invention
This invention broadly relates to a matrix clamp used in dental procedures. More particularly, the present invention is directed toward a clamp used to hold a matrix band against a tooth while a restorative material is placed in a tooth cavity and while the material hardens.
2. Description of the Related Art
The practice of dentistry often involves treatment of teeth that have developed cavities. Cavities frequently result from a process of dental decay, where acids from food or bacteria dissolve the tooth enamel. If the cavity is not treated, the decay will continue to progress through the enamel and into the dentin.
To treat a tooth having a cavity, the practitioner typically removes the decayed portions of the tooth and then places a restorative material in the cavity. Dental restorative materials, also known as fillings, can be made of a composite material, a silver amalgam or gold. After the restorative material is packed into the prepared cavity, the material is shaped or carved by the practitioner to a configuration that preferably resembles the original shape of the tooth.
In some instances, such as when the cavity is relatively small and located in the middle of the occlusal surface (i.e., the outer or biting surface) of the bicuspid or molar teeth, the restorative material can be placed into the cavity and held in place by surrounding tooth structure until such time as the restorative material hardens. However, in other instances there may be insufficient tooth structure to securely hold the restorative material in place during placement and hardening. For example, if the cavity is located wholly or partially along one or more sides of the tooth, there may be insufficient adjacent tooth structure to hold the restorative material in place during the time that the restorative material is packed into the cavity by the practitioner and subsequently during the time that the restorative material is hardened.
As a consequence, dental practitioners often use a matrix band or a sectional matrix band to act as an auxiliary support that holds the restorative material in place during packing and hardening. Matrix bands and sectional matrix bands serve a function somewhat similar to formwork used when pouring concrete, in that the band provides an additional surface that helps to retain the restorative material in the cavity during placement, packing and hardening. Once the material has sufficiently hardened, the band is removed from the oral cavity and the surface of the restorative material that extends along areas where the band was previously located can be shaped or smoothed as needed to better blend in with the adjacent tooth surfaces.
Oftentimes, small dental wedges are placed in the interproximal spaces between the matrix band (or sectional matrix band) and the tooth adjacent the tooth that contains the cavity. The wedge serves to help retain the band in place and also helps urge the decayed tooth away from the adjacent tooth during the dental procedure. It is desirable to provide such a spacing during the restorative procedure, so that once the procedure is finished and the wedge and band are removed, the surface of the restorative material closely contacts the adjacent tooth.
While a variety of matrix band systems have been proposed in the past, there are generally two types of systems in current widespread use. One type of system includes an elongated matrix band and a clamp that is connected to opposite ends of the band. The band is placed around the circumference of the tooth and the clamp is then tightened to apply tension to both ends of the band, thereby pulling the band into place around the tooth. The clamp may include a screw mechanism that can be turned as desired to tighten the band against the sides of the tooth. Examples of such systems are described in U.S. Pat. No. 5,622,496 to Champagne and U.S. Pat. No. 3,517,444 to Tofflemire.
Another type of matrix band system includes a sectional matrix band. Sectional matrix bands typically extend only partially around the circumference of the tooth, and are most often placed in the interproximal regions (i.e., the regions directly adjacent neighboring teeth). The sectional matrix band is frequently held in place by one or more spring clamps that provide pressure against the band and adjacent tooth structure.
Sectional matrix bands are often made of a thin strip of plastic material or of metallic material such as stainless steel. The metallic material is preferably flexible and resilient, so that it can assume a curved shape that closely matches the original curved shape of the sides of the tooth. In some instances, the sectional band may be trimmed by the dental practitioner to better fit the interproximal space.
Conventional spring clamps used with sectional matrix bands are often made of a circular spring metal body and a pair of depending jaws or legs. The circular body has an inherent spring memory that urges the legs toward each other. To use the clamp, a specially-adapted pair of dental pliers is used to open the spring body against its inherent tension and move the legs apart from each other. Once the legs are placed in position straddling the interproximal area adjacent the wedge and band, the force on the pliers is released and the spring tension of the body then moves the legs toward each other and into a position in contact with the band and the wedge.
Once the spring clamp is properly placed, the legs of the clamp hold the band against the lingual side of the tooth (i.e., the side of the tooth facing the patient's tongue) next to the interproximal area and also against the buccolabial side of the tooth (i.e., the side of the tooth facing the patient's cheeks or lips) next to the interproximal area. In that position, the legs also bear against the wedge, which serves to slightly separate the decayed tooth from the adjacent tooth located on the other side of the wedge.
While the matrix band systems described above have been somewhat satisfactory in the past, there is a continuing need in the art to improve such systems. More particularly, it would be desirable to provide a matrix clamp for sectional matrix bands that is inexpensive and easy to use, and yet eliminates the need to use a separate hand instrument for placement of the clamp. It would also be preferable to avoid use of the dental wedge in the procedure if at all possible.